Recently I heard a presentation by Dr. Tapio Schneider  of the California Institute of Technology . Some of what I recall includes the following. Carbon dioxide content in the atmosphere has risen perhaps 50% in a few hundred years. Using data such as ones leading to that percentage, seemingly “all” computerized climate models predict decreases in precipitation in areas of the world already considered arid. The biggest uncertainties in the science and modeling are twofold. First, people are unable to account for removal – on an ongoing basis – from the atmosphere of carbon dioxide equivalent to half of that produced by people. Second, relevant phenomena related to reflection and other interactions with light of clouds are not “that well” understood.
I recall working as a physicist at the University of California  Lawrence Livermore (National) Laboratory  in the mid 1970s. Two scientists who worked in offices “around the corner” (on the same floor as did I) were, based on measurements and their computer model, beginning to “sound an alarm” regarding depletion of ozone above